VARIATIONS OF GARTER-SNAKES. 57 



by an obscurity of tbese markings. In 1892 be apparently recog- 

 nized tbis fact and tbe near relationsbips of tbese forms, as be 

 describes tbem all as forms of niacrostfrnma, evidently including 

 insigniarum specimens witb obscure markings botb of tbe yellow (3) 

 and black (2) pbases, since be states tbat tbe type of macrostemma 

 is intermediate in color between insigniarum and flavilahris. In 

 1900 be carried tbis fartber and reduced jlavilahris and insigniar-um 

 to tbe standing of varieties, but defined macrostemma (insigniarum) as 

 being larger, darker colored and baving tbe spots and bands indistinct 

 and tbe parietal spots generally absent, as distinguisbed from 

 favilahris witb its brighter colored ground, }'ellow labials, stripes, 

 belly, and parietal spots. As w^e bave sbov»n in tbe description of 

 tbe color })bases, tbe ground color in tbe original insigniarum form is 

 yellow, so tbat althougb Cope was justified in combining insigniarum 

 and macrosteninto, as all intermediate color pbases occur, be bas 

 limited bis description to include only tbe dark forms, pbase 1 and 2, 

 and placed tbe name insigniarum in tbe synonymy of macrostemma, 

 but at tbe same time excluded tbe color pbase to wbicb it was 

 originally given, putting tbese specimens with favilahris. Tbat tbis 

 is actually tbe case is furtber sbown b}^ tbe fact tbat be subsequently 

 labeled several specimens of tbe yellow pbase (3) as favilahris. 



As a matter of fact it is absurd to attempt to distinguisb subspecies 

 on tbese color pbases, and, indeed, impossible to do so and still observe 

 geograpbic probability. If we ignore all questions of nomenclature 

 and examine tbe color pbases, it will be found tbat numbers 1, 2, 

 and 3 may all occur in the same locality and intergrade perfectly, 

 but seem to be quite distinct from pbase 4, witb its more distinct 

 markings. If we examine tbe range of tbe specimens, bowever, w^e 

 will find that the color phases 1,2, and 3 are only represented in tbe 

 southern part of Mexico, and that they include all of the specimens 

 taken about tbe lakes in this region (Patzcuaro, Chalco, Xochimilco), 

 while phase 4 is found to the north in Arizona, Chihuahua, Durango, 

 and Guanajuato, and in Veracruz and Puebla. They can therefore 

 hardly be classed as either individual or racial variations, and since 

 they are not sexual, males and temales being found of either color, 

 the suggestion arises at once that they may be due more or less to 

 local environmental influences. This explanation is enforced b}' the 

 fact that the specimens taken about the lakes Chalco and Patzcuaro 

 (the forms with obscure markings) represent the aquatic forms whose 

 habits have been described, while those in the more arid regions are 

 the phase 4. Tliis explanation must be taken with extreme caution, 

 how^ever, for in very few cases is there data witb individual specimens. 

 It is advanced principally to call attention to the need of detailed 

 study on tbis point. 



Enough has been said to establish the homogeneity (f tlie form 

 megahps throughout its range. Tliis uniformity, wliich is in bar- 



